(1) Field of the Invention
The present invention relates to the field of performance measurement of devices within a communication system or network. More specifically, the present invention relates to the field of device performance measurement, fault detection and fault isolation within a ring based communication network by monitoring of traffic through individual parts of the network.
(2) Prior Art
Local area networks, also called "LANs," are largely used as a means to provide a communication network between various workstations, peripherals and elements of a computer system. Using local area networks, several otherwise independent computer systems may be communicatively coupled together so that each may share information with the others or one may control the other. Also, other computer system components or peripherals, such as disk drives, printers, modems, display devices, etc. may be coupled as stations or nodes to the local area network for communication and control between the workstations. Therefore, within a local area network several workstations may share information between other workstations and/or control other computer system components or peripherals. Local area networks have proven to be a very efficient and advantageous way to interconnect office computers and peripherals into centralized computer systems for information exchange and timesharing of computer peripherals. Therefore, systems are needed and desirable that can monitor the communication performance of such network devices and transmission pathways and that can be used to detect and isolate faults.
In a ring communication topology protocols (i.e., FDDI and token ring), units or nodes of the communication network may be communicatively interconnected in a close-end ring fashion with each node occupying a particular position within the overall communication network. Communication packets (messages) within the network will travel in the same direction along a closed loop communication pathway between each station. Messages that traverse this communication system mainly include the token (in token ring networks), dam frames, and network control packets. These messages are often referred to as communication traffic. A particular node (i.e., network management station) within the communication system may be designated as an active monitor which will control several communication features of the communication ring network.
Managing a local area network requires a determination of the degree of effectiveness that a port or its attached device functions on the network with relation to the remainder of the network. In order to simplify the above process, it would be advantageous to determine if a particular port (station or link) is functioning better, worse, or about the same as the rest of the devices on the network. Aspects of the present invention perform such function. It would further be advantageous to measure error rates on a ring based network and compare performance of a particular port or its attached device to the remainder of the network. The present invention performs such functions. It would further be advantageous to perform the above functions within the port logic of the communication ports of the system. The present invention provides such capability.
The communication scheme of a ring topology network requires that each and every node of the ring be operating properly to repeat ("recast") messages over the ring. A disastrous effect occurs within a communication ring if one particular node or communication link malfunctions and will not accurately repeat messages thus reducing the overall performance of the devices on the network. A faulting communication line, port, or station may intermittently interrupt or break communication flow causing message dataframes to be lost and/or corrupted. This may severely reduce the performance of the entire ring network as messages may not flow past the malfunctioning node or transmission line. Therefore, it would be advantageous to provide a system within a ring based communication network that can be used to determine the degree of performance of each port or attached device on the network. It would be advantageous to utilize the performance information for each port to then detect and determine the location of transmission faults. The present invention offers such capability.
Several reasons may cause a node along the communication ring to malfunction and thus lose or corrupt message packets. First, a node having an incorrect communication frequency may be inserted into the token ring network. The incompatible frequency will lock out the newly added node from the network. Or, a faulty cable or receiver may inject noise into the system and cause errors in message packets to be undetectable. In any of a number of different scenarios, it would be advantageous to be able to determine how particular stations are performing with respect to the entire communication network and use this information for fault detection and isolation. The present invention offers such an advantageous solution.
Communication networks of the prior art are composed of prior art concentrators. Due to the nature of the electronics within the concentrators of the prior art, the messages traveling through the ports to adjacent stations may not be read or analyzed by the ports themselves because clocking signals within the dataframes may not be recovered by the port logic. In effect, the port logic of prior art concentrator designs is rather limited. The decoding required to read the clocking signal from the serial data flowing between the stations (and ports) is a complex process that is not supported within all concentrators of the prior art design. In this sense, the ports and port logic of the prior art are passive with respect to analyzing the dataframes that pass on the communication ring. Communication errors in the prior art systems are often non-isolatable due to the difficulty of monitoring the messages into and out of the legs of the network. Therefore, it would be advantageous to provide ports and port logic within a given concentrator that have enough intelligence to analyze the data streams flowing to and from the coupled stations, and further, it would be advantageous to use such functionality to help provide fault detection and isolation capabilities for the overall network. The present invention offers such advantageous capabilities.
Because prior art token passing systems do not offer the ability for a port to analyze the dataframe packets that traverse the network, any form of dataframe analysis would have to occur within the stations of the network. This is not advantageous because a system for fault analysis that is to watchdog over the communication stations of the network should not execute within or rely on the proper functioning of those same stations for its own error free operation. Given this system, a faulty station may corrupt these watchdog functions resulting in the faulty station not being detected. It would be advantageous to place any fault detection and isolation system outside the scope of the network stations so that the system does not rely upon the error free operation of these stations for its own proper operations. The present invention provides such an advantageous system.
Accordingly, it is an object of the present invention to provide a mechanism within a ring based network for device performance measurement, fault detection, and fault isolation. It is further an object of the present invention to provide a mechanism to determine how well a port or attached device (station) functions on the network compared to the remainder of the network by determining if a particular port (station or link) is functioning better, worse, or about the same as the rest of the communication network. It is yet another object of the present invention to provide a mechanism that can measure error rates on a ring based network and compare performance of an attached device to the rest of the network (i.e., on several ports in a network concentrator) in order to gauge overall error performance and indicate where in the network communication errors are occurring. It is yet another object of the present invention to provide a mechanism that may monitor, at each port, the number of messages entering and exiting each port that originate from a targeted source address. It is an object of the present invention to compile, for each port, an indication of the performance of that port and utilize this information reported from each port to detect and isolate communication hulls. It is further an object of the present invention to accomplish the message monitoring aspects of the above features within the port logic of the ports of the communication network of the present invention. These and other objects of the present invention not specifically stated herein will become evident upon review of the discussions of the present invention to follow.